New high-molecular-weight contrast agents based on polyamidoamine (PAMAM) dendrimers for targeted imaging of malignant tumors characterized by overexpression of human epidermal growth factor receptor (EGFR) and human alpha-fetoprotein receptor (RECAF) were designed. Conjugates of second (G2) and third (G3) generation polyamidoamine dendrimers with 1,4,7,10-tetraazocyclodecane-1,4,7,10-tetraacetic acid (DOTA) were obtained. The quantitative composition of the conjugates was determined by 1 HNMR spectroscopy. It was shown that four out of the 16 terminal NH 2 groups in G2-DOTA and nine out of the 32 groups in G3-DOTA were modified with DOTA. The morphology, size, and charge of the synthesized macromolecules were characterized by dynamic light scattering and electrophoresis. Gadolinium(III) was loaded into the conjugates and the Gd content was determined by atomic emission spectroscopy. For increasing the selectivity of accumulation in the tumor cells, two recombinant proteins able to bind selectively to EGFR and RECAF, namely, human recombinant epidermal growth factor (rEGF) and human recombinant 3rd domain of alpha-fetoprotein (3dAFPpG), were conjugated with G2 and G3 dendrimers. The conjugates containing vector molecules were mainly accumulated via clathrin-dependent endocytosis, whereas G2-DOTA and G3-DOTA were absorbed via caveolin-dependent endocytosis and macropinocytosis. The dendrimer conjugates with vector molecules were intensely accumulated in A549 cells characterized by high expression of EGFR (Herl) and RECAF, whereas the accumulation of conjugates in the control K562 cells (with low expression of Her1) and in the CD14 − population of human unstimulated mononuclear white blood cells was insignificant. The 3dAFPpG-conjugated dendrimers were partly recycled. All synthesized conjugates had a rather low toxicity in the range of 350–450 µmol L −1 (IC 50 ).

中文翻译：

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基于聚酰胺胺树枝状聚合物的造影剂靶向和非靶向递送系统的细胞内化

设计了基于聚酰胺胺 (PAMAM) 树枝状大分子的新型高分子量造影剂，用于以人表皮生长因子受体 (EGFR) 和人甲胎蛋白受体 (RECAF) 过表达为特征的恶性肿瘤的靶向成像。获得了第二代 (G2) 和第三代 (G3) 聚酰胺胺树枝状聚合物与 1,4,7,10-tetraazocyclodecane-1,4,7,10-四乙酸 (DOTA) 的缀合物。缀合物的定量组成通过 1 HNMR光谱测定。结果表明，G2-DOTA中16个末端NH 2 基团中的4个和G3-DOTA中32个基团中的9个被DOTA修饰。通过动态光散射和电泳表征合成大分子的形态、大小和电荷。钆 (III) 被加载到共轭物中，Gd 含量通过原子发射光谱法测定。为了增加肿瘤细胞中积累的选择性，两种能够选择性结合 EGFR 和 RECAF 的重组蛋白，即人重组表皮生长因子 (rEGF) 和人重组甲胎蛋白第三域 (3dAFPpG)，与 G2 偶联和 G3 树枝状聚合物。含有载体分子的结合物主要通过网格蛋白依赖性内吞作用积累，而 G2-DOTA 和 G3-DOTA 则通过小窝蛋白依赖性内吞作用和巨胞饮作用吸收。与载体分子结合的树枝状聚合物在 A549 细胞中大量积累，其特征是 EGFR (Herl) 和 RECAF 的高表达，而在对照 K562 细胞（Her1 低表达）和 CD14 - 人类未刺激单核白细胞群中缀合物的积累是微不足道的。部分回收了 3dAFPpG 共轭树枝状聚合物。所有合成的偶联物在 350–450 µmol L -1 (IC 50 ) 范围内都具有相当低的毒性。